FRIDAY, March 26 (HealthDay News) -- Shift work increases the risk for irritable bowel syndrome (IBS), new research shows.

"We know that people participating in shift work often complain of gastrointestinal symptoms such as abdominal pain, constipation and diarrhea," Dr. Sandra Hoogerwerf, an assistant professor of internal medicine at the University of Michigan Medical School, said in a university news release. "These are the same symptoms of IBS."

In a study involving 399 nurses, she and her colleagues found that those doing shift work -- especially rotating shifts -- were significantly more likely to develop IBS and abdominal pain than were those who worked a standard daytime schedule.

The study was published online recently in the American Journal of Gastroenterology.

"We know the colon has its own biological clock and that's what increases the likelihood of having a bowel movement in the first six hours of the day," Hoogerwerf said. "Shift work can cause chronic disruption of that biological rhythm, resulting in that clock to constantly be thrown off and needing to adjust, creating symptoms of diarrhea, bloating, constipation and abdominal pain and discomfort."

The study findings suggest that sleep disturbances do not completely explain the link between shift work and IBS or abdominal pain.

"The question now for further research is if IBS and abdominal pain is an underlying manifestation of a circadian rhythm disorder," Hoogerwerf said.